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Richard Courts
Dec 18, 2009 - 8:06PM
Suspected electrolysis attack sealed water system
During the season the header tank to the heat exchanger started to lose water. I traced the leakage to the bent form of copper pipe which runs from the lower part of the engine block to the manifold. I temporarily fixed it by passing over a cut strip of plastic pipe and fastening it with two jubilee clips. This pipe passes close and across the front of the engine block.
When I took the pipe to the local metal worker for repair which he copper welded he remarked that he did not believe the pipe leak was caused by chafe but some form of static electrolysis as the hole was perfectly round. He mentioned that I should search around the engine block for a stud in which can be placed a wasting anode to protect the dissimilar metal situation. Has anyone experienced this problem before or can endorse a solution? The engine and associated metal work is already protected with a wire leading to an anode externally on the hull but I gather this is not the problem as it is considered a different form of static?
SeaDog Name (if owner or crew) Milton Lass
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John Lansdell
Dec 18, 2009 - 10:14PM
Re: Suspected electrolysis attack sealed water system
I've had a look at the Perkins engine manual and can find no trace of a sacrificial anode mentioned within the coolant system. I've never worked on this engine, because we have fitted a Kubota. (The orignal Perkins was full of water when we bought the boat. ) I'd like to hear what comments Eric may have on this problem.
SeaDog Name (if owner or crew) Twotails
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Graham
Dec 18, 2009 - 10:24PM
Re: Suspected electrolysis attack sealed water system
I have been trawling the Internet on this one and like John I do not think the engine originally had one. I certainly don't recall changing one in the 9 years that we had a Perkins engine before changing it for the BetaMarine.
There are many 'hits' talking about zinc pencil anodes on the heat exchanger body.
Personally I was never happy with the thought of copper pipes as part of the cooling system (though I know they were often used). I guess the fact that these pipes seem to last about 30 years must count for something, but maybe an anode would have made it last forever!
As you say I am sure Eric will have a view on this, and I would do whatever he recommends!
Graham
SeaDog Name (if owner or crew) Dougal
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Phi
Dec 19, 2009 - 11:39AM
Re: Suspected electrolysis attack sealed water system
Hi
I have checked my Perkins manual and the owner instruction hand book, there is no engine anode. I have also spoken to my instructor on the RYA Engine course and he confirms that there is no anode. However it is important to keep the anti freeze fresh as this has anti corrosive properties.
I would suggest that as you are draining the system that you take the opportunity of cleaning the heat exchanger and checking the thermostat (which cannot be accessed with the heat exchanger on).
Good luck
SeaDog Name (if owner or crew) Soyakaze
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E Richardson
Dec 19, 2009 - 1:59PM
Re: Suspected electrolysis attack sealed water system
Hi Richard
The majority of Perkins engines are fresh water cooled as in motor vehicled etc, they do not have Anodes fitted as standard as they are not needed. It is vital that they have a decent strength antifreeze mix to inhibit corrossion. The antifreeze should be changed every couple of years or so to maintain its inhibitors.
Anodes were fitted where they were used with direct seawater cooling, but Perkins never recommended there use in that manner. A few ship yards used them this way to cut costs and the Anodes were what you would call yard fit items and differed widely in position and type.
You mention the hole in the copper pipe, is this the pipe across the front of the engine? I have found one of those with a hole in. It was caused by rubbing thin from the drive belt at some time and then bursting through as a pin hole due to water pressure.
Most modern fresh water cooled engines like the Beta have Anodes fitted into the Alulminium heat exchanger, but into the seawater end to protect the heat exchanger body. These are of the Pencil type and certainly waste away showing that they are doing the job.
The old style heat exchangers tend to be of thicker section so generaly get away with out protective Anodes for many years.
Your engine should be connected to the Anode on the hull, and this connection needs to be of a high standard with very little resistance, (easily measured with a multi meter). If this is done you are very unlikely to have any problems.
Eric
SeaDog Name (if owner or crew) Ex Taliesin
Richard Courts
Dec 20, 2009 - 1:09PM
Re: Suspected electrolysis attack sealed water system
Thank you Eric and others on this matter. There are a couple of points in Eric's email which I am taking on board. Firstly I am guilty of not refreshing the antifreeze mix regularly, just topping up, so this will now become regular practice. Secondly the copper pipe does pass in front of the engine although the hole was not formed on the belt side but adjacent to the engine block, the distance between block and pipe was very little and as a precaution against any possible chafe will sleeve the copper pipe in that area in plastic tube as I did to stop the original leak; I will also make absolutely sure that there is still a good anode connection to the hull.
Many thanks for all your observations.
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